I'm trying to monitor Tomcat 6.0 using JMX. Specifically, I want to monitor the number of active threads servicing requests so I can get an alert if it approaches the maximum. While I have JMX monitoring working in general, I can't seem to get the number of threads. Everything I have read suggests looking at:
And examining the currentThreadsBusy attribute. Unfortunately, I only ever seem to get -1 as a value. I've tried it on five different Tomcat instances and I always get -1.
Is there something I'm missing? Should I be looking at a different value?
I'm using an Executor, so I checked the activeCount attribute in the Executor and it always returns 0.